Note that there are many variations of lime available but only quicklime is considered suitable for lime stabilisation in the pavement construction industry and general field construction activities. Quicklime is calcium oxide (CaO) supplied commercially in a dry powder form. Agriculture Lime is a calcium carbonate (CaC03) and not suitable for pavement construction. Hydrated Lime is calcium hydroxide (Ca(OH)2) often used in the laboratory for lime saturation testing, not generally used on site for pavement construction.

Hydrated lime (calcium hydroxide), is produced by reacting water with quicklime (calcium oxide). CaO + H2O => Ca(OH)2. When calculated using the atomic weights, this converts practically to 5t Quicklime + 3t Water => 7t Hydrated lime + 1t Water Evaporation.

The pozzolanic reaction between lime with water and the silica and alumina in clay results in an ionic exchange, which permanently realigns the clay particles forming friable conglomerates. The new alignment of the particles provides less ability for the clay to absorb water around the particles. This makes the clay more waterproof, less expansive and therefore reduces the plasticity and linear shrinkage. The PI is often more than ½ and the shrinkage is often 10% of what it was. Practically this results in improved permeability less shrinkage cracking providing less chance of piping failure and seepage.

In a lime saturated environment (typically 3% to 4% quicklime), the clay-alumina and clay-silica become available to react with the free calcium to form calcium aluminates or silicates. The pozzolanic reaction is illustrated by the following equations:

Ca2+ + OH- + Available Clay Aluminium Calcium Aluminate Hydrate (CAH)
Ca2+ + OH- + Available Clay Silica Calcium Silicate Hydrate (CSH)